docs: def _use(cls, ec):
          """
          underly implement of use
          """
          # class ConnectModel(cls):
          #     pass
          ConnectModel = type(cls.__name__, (cls,), {})
  
          ConnectModel.tablename = cls.tablename
          ConnectModel._base_class = cls
          if isinstance(ec, (str, unicode)):
              ConnectModel._engine_name = ec
          elif isinstance(ec, Session):
              ConnectModel._engine_name = ec.engine_name
              ConnectModel._connection = ec
          return ConnectModel